From the Cree datasheets, at 1 amp the XP-G R5 is 348-370 lumens while the R5 XT-E is 320-340. So the XT-E is acting a little more like an XP-G R4. However the XT-E output is rated at a higher temperature and if the XP-G were rated at the same temperature it would be a little lower too. So apples to apples, you could increase the XT-E output by 15% and get 368-391 lumens at 25 degrees C to compare with the XP-G. Now the XT-E is a bin brighter at 1 amp.
Around 260-300 OTF depending upon conditions and lense/bezel used according to my own measurements. The XT-E should be around 8-10% more efficient in total output.
At Vin of 3.3V, you are getting below Vf at 1A for the LED so the current draw is probably down as well. The driver is taking some of the Vin for itself.
I don't think the spec temperature means anything. It is just a setting at which they measure performance. Maybe some people complained that Cree was evaluating their LED's at room temperature when, realistically, the LED is going to get hot very quickly and it would be more realistic to measure the output when the LED is hot. The datasheets allow you to generate numbers at any temperature you want, it's just the default (100%) value is at 25 degrees for the XP-G while for the XT-E it is 100% at 85 degrees.
I wonder why they changed the temperature? Could it be that the carbide base of these chips doesn't transfer heat as well so they expect them to actually run hotter?
On the contrary, XT-E has a thermal resistance to the base = 5 degr./W and the XP-G has 6 degr./W
I think they started binning XB-D and XT-E at 85'C as a new policy. You can easily make a verification test at that temperature. It is more difficult to set up a test at the north pole
Got my XT-E drop-in from KaiDomain today. I love that it has 3 modes using the NANJG AK-47A driver. The drop-in has a smooth reflector, but the beam has a definite yellow center. The edge of the hotspot is a little green or yellow. Not sure if Cree will be able to work this out.
I tried some 3000K warm white XT-E in a homebrew 4x Mag mod that I'm not done with yet. I tried a variety of reflector shapes, sizes and textures and even a few optics. The one and only thing I tried that gave pleasant uniform color (instead of banana-berry swirl) were Ledil Boom Spot 20mm microfaceted reflectors. I'd venture a guess that a Fraen 34mm microfaceted reflector might look good as well, but I don't have any spares or room for them in the light I'm building.
Remember when the XMLs first came out we got horrible color change like that also. Hopefully quality control will come up after a while and we will get more even color dispersion